Fragility

Fragility refers to the tendency of a system, component, or material to fail or be damaged by small perturbations. It is a relative measure that depends on the magnitude of the perturbation, the system’s design, state, and environment. In risk analysis and engineering, fragility describes how likely a given item is to fail under a specified level of stress or hazard.

In materials science, fragility is related to brittleness but is not identical. Brittle materials crack with little or no plastic deformation, but fragility also encompasses susceptibility to failure due to flaws, stress concentrations, deterioration, or adverse environmental conditions. Factors influencing fragility include microstructure, impurities, temperature, loading rate, and the presence of defects.

In engineering, fragility is often formalized through probabilistic methods. Fragility curves or functions express the probability of failure as a function of hazard intensity or demand. These tools support reliability assessment, structural risk evaluation, and the design of safety margins.

In everyday usage, fragility describes objects that require careful handling, such as glassware or delicate electronics. In broader terms, some systems—ecological, financial, or social—are described as fragile if shocks produce disproportionate or cascading reactions, making them more prone to breakdown than robust systems.

Mitigation strategies aim to reduce fragility and enhance resilience. Approaches include appropriate material selection, safety factors, redundancy, damping and isolation, protective packaging, maintenance, and diagnostic testing. The concept is often discussed alongside robustness and, in some frameworks, antifragility, which emphasizes systems that improve under stress.